유선준 교수

The material behaviors of two types of bearing steels at hot working conditions are investigated. Stress-strain curves at various temperatures (900–1300°C) and strain rates (1–50/s) are obtained by compression tests with a computer controlled servo-hydraulic Gleeble 3800 testing machine. Elongation and reduction of the area are also obtained by tensile tests with the Gleeble 1500 testing machine. Flow stresses are calculated from the experiments and are used to predict the temperature distributi

OBJECTIVE: The study compared the morphometric changes of the cervical spinal cord using dynamic magnetic resonance imaging (MRI) in patients with cervical spondylotic myelopathy (CSM) and assessed the correlation with kinematic changes, cord cross-sectional area (CSA), and high signal intensity (SI) on T2-weighted imaging (T2WI). METHODS: Patients with CSM were evaluated through dynamic MRI for sagittal and axial CSA changes of the cervical cord, cerebrospinal fluid (CSF) reserve ratio, degree

OBJECTIVE: To evaluate the impact of the K-line and canal-occupying ratio (COR) on surgical outcomes in patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: Patients with cervical myelopathy due to multilevel OPLL who underwent decompression surgery (anterior or posterior) from 2013 to 2022, with 2-year minimum follow-up, were enrolled. Radiological evaluations included K-line, COR, OPLL type/level, and cervical parameters (C2 slope [C2S], T1 slo

OBJECTIVE: To evaluate the clinical significance of a negative K-line in the neck flexion position (FK-line [-]), which indicates that cervical ossification of the posterior longitudinal ligament (OPLL) crosses the K-line during flexion, and to compare surgical outcomes between laminoplasty (LP) and laminectomy with fusion (LF) for multilevel FK-line (-) cervical OPLL. METHODS: A total of 349 patients with multiple cervical OPLL who underwent posterior decompression surgery (LP or LF) with a min

OBJECTIVE: We aimed to investigate the incidence of delayed-onset neurological deficits (DONDs), DOND-related reoperation rates following adult spinal deformity (ASD) surgery, and efficacy of transverse process hooks (TPHs) at the uppermost instrumented vertebra (UIV) compared to pedicle screws (PSs). METHODS: We included 90 consecutive patients who underwent instrumented fusion from the sacrum to the distal thoracic spine for ASD, with a minimum follow-up of 24 months. Clinical and radiological

Study Design Retrospective cohort study. Objectives To compare the outcomes of C2 dome-like laminoplasty (C2-Dom LP) and C2 laminectomy with fusion (C2-LF) in patients with C2-involving ossification of the posterior longitudinal ligament (OPLL) and to identify radiological predictors that guide optimal surgical selection. Methods A retrospective analysis of 143 patients (C2-Dom LP, 71; C2-LF, 72) was performed. Radiological evaluations were C2 cross-sectional area (CSA), cervical range of motion

Background/Objectives: To evaluate the clinical and radiological outcomes of surgical interventions stratified by dynamic K-line status and to identify predictors of neurological recovery in multilevel cervical ossification of the posterior longitudinal ligament (OPLL). Methods: This study analyzed 535 patients with multilevel cervical OPLL who underwent anterior cervical discectomy and fusion (ACDF), laminoplasty (LP), or laminectomy with fusion (LF), with a minimum 24 months of follow-up. Pati

PURPOSE: Unilateral biportal endoscopic discectomy (UBE) is an effective and minimally invasive technique for the treatment of degenerative lumbar diseases. However, reoperation may be required, and evidence on how risk factors vary according to the timing of reoperation remains limited. This study aimed to identify the clinical and radiologic factors associated with short-term (<6 months) and long-term (≥6 months) reoperations following UBE. MATERIALS AND METHODS: This retrospective study inclu

Background/Objectives: Optimal trajectories for S2-alar-iliac (S2AI) screw placement have been widely studied; however, in fluoroscopy-assisted free-hand techniques, exact reproduction is rarely achievable. This study aimed to quantify direction-specific safety margins around patient-specific optimal trajectories and to determine their relationship with pelvic parameters. Methods: We retrospectively analyzed patients who underwent S2AI screw fixation with available preoperative and postoperative